ZX81 (EightyOne) WIP¶

Background¶

81-libretro is an work in progress port of the EightyOne (a.k.a. THE Sinclair Emulator) to libretro. The classic ZX81 games are all over the Internet, but check the colorized folder for games with Chroma 81 support. There are also many original games for the Zeddy, check Bob's Stuff for some high quality games.

The EightyOne core has been authored by

Michael D Wynne

The EightyOne core is licensed under

GPLv3

A summary of the licenses behind RetroArch and its cores can be found here.

EightyOne emulates a number of ZX80, ZX81, clones, and other computers based on the same hardware:

Sinclair ZX80
Sinclair ZX81
Timex TS1000
Timex TS1500
Lambda 8300
Ringo R470
MicroDigital TK85
Jupiter ACE

However, 81-libretro only emulates the Sinclair ZX81 with 16Kb RAM for now. Other machines will be added as time permits. Push requests are welcome.

The port correctly loads and runs some many games I have around in the p format. tzx format is also supported.

EightyOne also emulates some ZX Spectrum machines, but those were left out of this core on purpose.

Extensions¶

Content that can be loaded by the EightyOne core have the following file extensions:

.p
.tzx
.t81

Databases¶

RetroArch database(s) that are associated with the EightyOne core:

Sinclair - ZX 81

Features¶

RetroArch-level settings or features that the EightyOne core respects.

Feature	Supported
Restart	✔
Screenshots	✔
Saves	✕
States	✔
Rewind	✔
Netplay	✔
Core Options	✔
RetroAchievements	✕
RetroArch Cheats	✕
Native Cheats	✕
Controls	✔
Remapping	✕
Multi-Mouse	✕
Rumble	✕
Sensors	✕
Camera	✕
Location	✕
Subsystem	✕
Softpatching	✕
Disk Control	✕
Username	✕
Language	✕
Crop Overscan	✕
LEDs	✕

Directories¶

The EightyOne core's directory name is 'EightyOne'

The EightyOne core saves/loads to/from these directories.

RetroArch's State directory

'content-name'.state# (State)

Geometry and timing¶

The EightyOne core's core provided FPS is 50
The EightyOne core's core provided sample rate is 44100 Hz
The EightyOne core's core provided aspect ratio is (Ratio)

Auto-configuration¶

Since configuring the core for each game can be a tedious task, the EightyOne core features auto-configuration. Games that support auto-configuration are listed in the src/gamedb/gamedb.json file, along with some information and the configuration required to play them.

Currently, there's no way to change the auto-configuration settings short of recompiling the core after making the changes. If you feel the provided auto-configuration could be better or has bugs, please open an issue.

Colorization¶

Colorization works by loading a program prior to loading the game. This program will check if the Chroma 81 expansion is installed, and, if it is, configures the colors of the ZX81 characters, and then loads the original game, which runs unaware that it's playing with colors.

Since the EightyOne core can't load arbitrary programs from the file system, the colorization program and the game must exist in the same file.

Core options¶

The EightyOne core has the following option(s) that can be tweaked from the core options menu. The default setting is bolded.

Settings with (Restart) means that core has to be closed for the new setting to be applied on next launch.

Tape Fast Load (Off/On)

Instantly loads files if enabled, or disable it to see the moving horizontal lines while the game loads.
8K-16K Contents (auto/ROM shadow/RAM/dK'tronics 4K Graphics ROM + 4K RAM)

Selects the contents of memory addresses between 8192 and 16383, a shadow copy of the ROM, 8K of RAM, or dK'tronics 4K ROM plus 4K of RAM.
High Resolution (auto/none/WRX)

Enables WRX high resolution.
Emulate Chroma 81 (auto/Off/On)

Enable the Chroma 81 interface (colorization).

Emulate Chroma 81 - auto/On

Emulate Chroma 81 - Off

Video Presets (clean/tv/noisy)

Change how the video is emulated (if Chroma 81 is enabled, the video is set to "clean" regardless of this option).

Video Presets - clean

Video Presets - tv

Video Presets - noisy

Sound emulation (auto/none/Zon X-81)

Enables sound emulation.
Joypad Left mapping (auto/default/new line/shift/space/./0/½/¾/⅚/⅞/9/a/b/c/d/e/f/g/h/i/j/k/l/m/n/o/p/q/r/s/t/u/v/w/x/y/z)

Maps this joypad button to a keyboard key, defaults are the cursor keys for the directional pad and '0' to all the other buttons.
Joypad Right mapping (auto/default/new line/shift/space/./0/½/¾/⅚/⅞/9/a/b/c/d/e/f/g/h/i/j/k/l/m/n/o/p/q/r/s/t/u/v/w/x/y/z)

Maps this joypad button to a keyboard key, defaults are the cursor keys for the directional pad and '0' to all the other buttons.
Joypad Up mapping (auto/default/new line/shift/space/./0/½/¾/⅚/⅞/9/a/b/c/d/e/f/g/h/i/j/k/l/m/n/o/p/q/r/s/t/u/v/w/x/y/z)

Maps this joypad button to a keyboard key, defaults are the cursor keys for the directional pad and '0' to all the other buttons.
Joypad Down mapping (auto/default/new line/shift/space/./0/½/¾/⅚/⅞/9/a/b/c/d/e/f/g/h/i/j/k/l/m/n/o/p/q/r/s/t/u/v/w/x/y/z)

Maps this joypad button to a keyboard key, defaults are the cursor keys for the directional pad and '0' to all the other buttons.
Joypad A button mapping (auto/default/new line/shift/space/./0/½/¾/⅚/⅞/9/a/b/c/d/e/f/g/h/i/j/k/l/m/n/o/p/q/r/s/t/u/v/w/x/y/z)

Maps this joypad button to a keyboard key, defaults are the cursor keys for the directional pad and '0' to all the other buttons.
Joypad B button mapping (auto/default/new line/shift/space/./0/½/¾/⅚/⅞/9/a/b/c/d/e/f/g/h/i/j/k/l/m/n/o/p/q/r/s/t/u/v/w/x/y/z)

Maps this joypad button to a keyboard key, defaults are the cursor keys for the directional pad and '0' to all the other buttons.
Joypad X button mapping (auto/default/new line/shift/space/./0/½/¾/⅚/⅞/9/a/b/c/d/e/f/g/h/i/j/k/l/m/n/o/p/q/r/s/t/u/v/w/x/y/z)

Maps this joypad button to a keyboard key, defaults are the cursor keys for the directional pad and '0' to all the other buttons.
Joypad Y button mapping (auto/default/new line/shift/space/./0/½/¾/⅚/⅞/9/a/b/c/d/e/f/g/h/i/j/k/l/m/n/o/p/q/r/s/t/u/v/w/x/y/z)

Maps this joypad button to a keyboard key, defaults are the cursor keys for the directional pad and '0' to all the other buttons.
Joypad L button mapping (auto/default/new line/shift/space/./0/½/¾/⅚/⅞/9/a/b/c/d/e/f/g/h/i/j/k/l/m/n/o/p/q/r/s/t/u/v/w/x/y/z)

Maps this joypad button to a keyboard key, defaults are the cursor keys for the directional pad and '0' to all the other buttons.
Joypad R button mapping (auto/default/new line/shift/space/./0/½/¾/⅚/⅞/9/a/b/c/d/e/f/g/h/i/j/k/l/m/n/o/p/q/r/s/t/u/v/w/x/y/z)

Maps this joypad button to a keyboard key, defaults are the cursor keys for the directional pad and '0' to all the other buttons.
Joypad L2 button mapping (auto/default/new line/shift/space/./0/½/¾/⅚/⅞/9/a/b/c/d/e/f/g/h/i/j/k/l/m/n/o/p/q/r/s/t/u/v/w/x/y/z)

Maps this joypad button to a keyboard key, defaults are the cursor keys for the directional pad and '0' to all the other buttons.
Joypad R2 button mapping (auto/default/new line/shift/space/./0/½/¾/⅚/⅞/9/a/b/c/d/e/f/g/h/i/j/k/l/m/n/o/p/q/r/s/t/u/v/w/x/y/z)

Maps this joypad button to a keyboard key, defaults are the cursor keys for the directional pad and '0' to all the other buttons.
Transparent Keyboard Overlay (Off/On)

If the keyboard overlay is transparent or opaque.

Transparent Keyboard Overlay - On

Transparent Keyboard Overlay - Off

Time to Release key in ms (100/300/500/1000)

How many milliseconds to wait before releasing the key pressed using the keyboard overlay.

Controllers¶

The EightyOne core supports the following device type(s) in the controls menu, bolded device types are the default for the specified user(s):

User 1 device types¶

None - Input disabled.
RetroPad - Joypad
Cursor Joystick - Joypad - Switch to this for joypad inputs.

User 2 device types¶

None - Input disabled.
RetroPad - Joypad
Sinclair Keyboard - Keyboard - Switch to this for keyboard inputs. Switch the User 1 device type to none if the correct keyboard inputs aren't being read.

Controller tables¶

Joypad¶

Attention

Use the Joypad mapping core options to configure the Cursor Joystick inputs.

User 1 Remap descriptors	RetroPad Inputs	Cursor Joystick
		Joypad B button mapping
		Joypad Y button mapping
		Keyboard overlay
		Joypad Up mapping
		Joypad Down mapping
		Joypad Left mapping
		Joypad Right mapping
		Joypad A button mapping
		Joypad X button mapping
		Joypad L button mapping
		Joypad R button mapping
		Joypad L2 button mapping
		Joypad R2 button mapping

Keyboard¶

RetroKeyboard Inputs	Sinclair Keyboard
Keyboard Backspace	VK_BACK
Keyboard Tab	VK_TAB
Keyboard Clear	VK_CLEAR
Keyboard Return	VK_RETURN
Keyboard Pause	VK_PAUSE
Keyboard Escape	VK_ESCAPE
Keyboard Space	VK_SPACE
Keyboard Comma ,	VK_COMMA
Keyboard Delete	VK_DELETE
Keyboard Keypad 0	VK_NUMPAD0
Keyboard Keypad 1	VK_NUMPAD1
Keyboard Keypad 2	VK_NUMPAD2
Keyboard Keypad 3	VK_NUMPAD3
Keyboard Keypad 4	VK_NUMPAD4
Keyboard Keypad 5	VK_NUMPAD5
Keyboard Keypad 6	VK_NUMPAD6
Keyboard Keypad 7	VK_NUMPAD7
Keyboard Keypad 8	VK_NUMPAD8
Keyboard Keypad 9	VK_NUMPAD9
Keyboard Keypad Period .	VK_DECIMAL
Keyboard Keypad Divide /	VK_DIVIDE
Keyboard Keypad Multiply *	VK_MULTIPLY
Keyboard Keypad Minus -	VK_SUBTRACT
Keyboard Keypad Plus +	VK_ADD
Keyboard Up	VK_UP
Keyboard Down	VK_DOWN
Keyboard Right	VK_RIGHT
Keyboard Left	VK_LEFT
Keyboard Insert	VK_INSERT
Keyboard Home	VK_HOME
Keyboard End	VK_END
Keyboard Page Up	VK_PRIOR
Keyboard Page Down	VK_NEXT
Keyboard F1	VK_F1
Keyboard F2	VK_F2
Keyboard F3	VK_F3
Keyboard F4	VK_F4
Keyboard F5	VK_F5
Keyboard F6	VK_F6
Keyboard F7	VK_F7
Keyboard F8	VK_F8
Keyboard F9	VK_F9
Keyboard F10	VK_F10
Keyboard F11	VK_F11
Keyboard F12	VK_F12
Keyboard F13	VK_F13
Keyboard F14	VK_F14
Keyboard F15	VK_F15
Keyboard Num Lock	VK_NUMLOCK
Keyboard Caps Lock	VK_CAPITAL
Keyboard Scroll Lock	VK_SCROLL
Keyboard Right Shift	VK_SHIFT
Keyboard Left Shift	VK_SHIFT
Keyboard Right Control	VK_CONTROL
Keyboard Left Control	VK_CONTROL
Keyboard Right Alt	VK_MENU
Keyboard Left Alt	VK_MENU
Keyboard Print	VK_SNAPSHOT

External Links¶

Last update: 2024-04-25